JP2013020093A - Image projection device, color correction method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projection device and a color correction method capable of automatically executing calibration of a correction value for color correction and color correction when satisfying preset conditions.SOLUTION: The image projection device for projecting an image corresponding to an input image to a screen 110 comprises: storage means 126 for storing a signal level of an image for calibration and an area where it exists in the screen 110; and control means 118 for causing a calibration of a collection value of each of 3D-LUT103 and 1D-LUT104 and color correction to be automatically executed under a condition that the input image includes the image for calibration.

Description

  The present invention relates to an image projection apparatus, a color correction method, and a program for performing color correction of a projected image.

  Projectors (image projection devices) are used in various lighting environments, but it is necessary to calibrate correction values for color correction of input images in consideration of the effects of actual wall colors and illumination light. . Conventionally, the user manually starts calibration by pressing an execution button or the like.

  For example, in Patent Document 1, a color conversion table that matches color information of an input image and color information of a projection image on a projection plane is generated, and the color of the input image is color-converted based on the color conversion table and is output to the projector. A projector color correction method for obtaining the above is disclosed.

  Further, Patent Document 2 projects a calibration image when there is no projection image, measures its XYZ value (based on the CIE standard) or RGB value, and based on the measurement data, a color correction table on the projection surface And a method of updating the brightness correction table.

JP 2003-323610 A Japanese Patent No. 3755593

  In the color correction method of Patent Document 1, in order to generate a color conversion table that realizes both color correction and calibration at the same time, a calibration image must be projected. If the illumination light changes during projection, it is necessary to regenerate the color conversion table, and if the user is presenting, the user must interrupt and project the calibration image.

  Further, in the method of Patent Document 2, it is necessary that there is no projection image between the color correction table generation step and the luminance correction table generation step. To perform the processing of both steps, the presentation is interrupted for correction. It takes a lot of time.

  The present invention provides an image projection apparatus, a color correction method, and a color correction program capable of automatically executing calibration and color correction of correction values for color correction when preset conditions are satisfied. For illustrative purposes.

  An image projection apparatus according to the present invention is an image projection apparatus that projects an image on a projection surface, corrects the color of an input image using a color correction table, and uses the brightness correction table to correct the input image. Color correction means for correcting the brightness, and the color correction table and the brightness correction table respectively hold so that the color information of the input image and the color information of the reflected light of the image projected on the projection surface match. Calibration means for calibrating the correction value, storage means for storing a signal level of a calibration image for performing the calibration and a region where the calibration image exists on the projection plane, and the input The calibration by the calibration means and the calibration on the condition that the image for calibration is included in the image And having a control unit for automatically performing color correction by the correction means.

  According to the present invention, it is possible to provide an image projection apparatus, a color correction method, and a program capable of automatically executing calibration and color correction of a correction value for color correction when a preset condition is satisfied. it can.

It is a block diagram of the image projection apparatus of this embodiment. It is a flowchart for demonstrating the operation | movement by the control means shown in FIG. It is a figure which shows the detail of S3 shown in FIG. It is a flowchart which shows the detail of S6 shown in FIG. It is a flowchart which shows the detail of S9 shown in FIG.

  FIG. 1 is a block diagram of the image projection apparatus of this embodiment. The image projection apparatus is configured by a liquid crystal projector or the like that projects an image onto a screen 110 that is a projection surface.

  In the image projection apparatus, the input signal processing 101 receives an input video signal (input signal) from an image supply apparatus such as a personal computer (PC), a DVD player, or a TV tuner (not shown). When the input signal is an analog signal, it is converted into a digital signal by an analog / digital converter in the input signal processing 101. When the input signal is a digital signal, the digital signal is sent to the storage unit 102 and the image detection unit 122 from the on-screen display (OSD) 124 that displays a menu or the like on the screen via the switch 125.

  The storage unit 102 stores a three-dimensional lookup table (3D-LUT) 103 and a one-dimensional lookup table (1D-LUT) 104. The 3D-LUT 103 is a color correction table such as a color gamut correction table or a color temperature correction table used for color correction. The 1D-LUT 104 is a luminance correction table such as a gamma table or a color balance table used for luminance correction.

  The liquid crystal display element driving circuit 105 performs double speed conversion and VT gamma correction necessary for driving the liquid crystal display element 107 that displays an image corresponding to the input image, and generates a liquid crystal display element driving signal.

  The liquid crystal display element 107 is illuminated with light emitted from an illumination optical system 106 including a high-pressure mercury lamp, and modulates incident light based on control by a liquid crystal display element drive signal from the liquid crystal display element drive circuit 105. The light beam emitted from the liquid crystal display element 107 is directed to the projection lens 108. The projection lens 108 performs a zoom operation with a zoom lens or the like, and projects the light flux from the liquid crystal display element 107 onto the screen 110 as a projection surface as projection light.

  The screen 110 such as a conference room is affected by external light such as sunlight incident from the external light illumination 109 or a window together with the projection light. Thereby, the color and brightness of the reflected light on the projection surface change. Further, the screen 110 itself has a slight color width with respect to the ideal white, and may be a non-ideal white, a blackboard, a color partition such as light blue, pink, or yellow.

  The color sensor 111 is a two-dimensional RGB color sensor such as a CCD camera, for example, and detects different wavelength regions of reflected light of the projected image on the screen 110 over the entire projection region. The image area designating unit 120 designates (detects) an area where a projection image exists on the screen 110.

  The detection result of the color sensor 111 is sent to the comparison calculation means 116 of the image comparison calculation unit 123. The detection result is sent as data indicating the XYZ value, data derived from the XYZ value (for example, coordinate values in a predetermined color space, xy chromaticity value, etc.), data deriving the XYZ value (for example, RGB values), and the like. . The region information by the image region specifying unit 120 is also sent to the comparison calculation unit 116 of the image comparison calculation unit 123.

  The XYZ value is a kind of color standard by the International Commission on Illumination (CIE), and the XYZ value can be converted into an RGB value. The Y value indicates luminance. That is, by projecting a reference image on the screen and detecting the XYZ values of the projected image on the screen by the color sensor 111, the color and brightness of the image can be obtained.

  The image comparison calculation unit 123 includes a correction update determination unit 114, a correction value storage unit 115, a comparison calculation unit 116, and a sensor reference value storage unit 121, and calculates a correction value to be calibrated in the table of the storage unit 102. .

  On the other hand, an input signal from a PC or the like is sent from the input signal processing 101 to the image detection unit 122 via the switch 125. The image detection unit 122 detects a reference image (signal level and area are known) necessary for calibration from the input signal in accordance with an instruction from the control unit 118.

  The image detection unit 122 includes an area designation unit 113 and an image level designation unit 117. The image detection unit 122 detects whether the input image based on the input signal includes a calibration image or a reference image that can be used for calibration. The calibration image or the reference image is stored in the storage unit 126. Since the reference image is an image suitable for calibration, it may be grasped as a calibration image.

  As a result, when the input image includes the calibration image stored in the storage unit 126, the image comparison calculation unit 123 calculates a correction value to be calibrated using the table in the storage unit 102.

  The control means 118 is a resolution converter (not shown) that converts the input signal (video signal) to a resolution suitable for the red, green, and blue liquid crystal display elements 107. Then, color correction and luminance correction are performed on the converted video signal. The control means 118 is composed of a microcomputer.

  The control unit 118 is a color correction unit that corrects the color of the input image using the 3D-LUT 103 that is a color correction table and corrects the luminance of the input image using the 1D-LUT 104 that is a luminance correction table. Function.

  In addition, the control unit 118 performs calibration for correcting the respective correction values held by the 3D-LUT 103 and the 1D-LUT 104 so that the color information of the input image matches the color information of the reflected light of the image projected on the projection surface. It also functions as a means.

  The control means 118 is connected to a storage means 126 for storing the signal level and area of a calibration image suitable for color correction. The storage unit 102 and the storage unit 126 do not need to be separate, and each piece of information may be stored in one storage unit. Further, the control unit 118 and the storage unit 126 may be communicable even if they are not physically connected.

  Further, the signal level is, for example, the value of a black signal or white signal or information corresponding thereto. The area represents a place of the image on the screen 110 (the entire screen may be the lower right or upper left of the screen). For example, the storage unit 126 stores a black image in a certain area at the lower right of the screen, a white image in a certain area at the upper left of the screen, and the like.

  The control unit 118 automatically performs calibration of the correction values of the table and color correction on the condition that the calibration image is included in the input image (as described above, this includes the output of the reference image). Run it. In this way, color correction is automatically executed when a certain condition is satisfied without any user operation (such as pressing a button).

  The image level specification unit 117 and the region specification unit 113 of the image detection unit 122 specify (detect) the signal level and region of the input signal as indicated by the dotted line in FIG. 3, and use the calibration stored in the storage unit 126. Automatically detect suitable images. Then, the image detection unit 122 transmits the detection result to the comparison calculation unit 116 of the image comparison calculation unit 123. The image detection unit 122 may set the signal level and the region stored in the storage unit 126 in advance, or may set the signal level and the region updated by the user setting and stored in the storage unit 126. .

  In FIG. 3, the coordinates of the upper left vertex (300, 200) and the coordinates of the lower right vertex in the entire screen of the rectangular area having the coordinates (0, 0) of the upper left vertex and the coordinates (1024, 768) of the lower right vertex in the xy coordinates. By setting (680, 576), the target area indicated by the dotted line is set. In the input signal level setting, each RGB color is set as 256 bits. Black signal detection is (0, 0, 0) +3 or less, gray 50% detection is (128, 128, 128) ± 3, and white signal detection is (255, 255, 255) −3 or more.

  The sensor reference value storage unit 121 stores data serving as a reference for the color sensor 111 adjusted by factory adjustment or the like according to input signal conditions suitable for calibration, a reference screen, and predetermined external light conditions. ing.

  The sensor reference value storage unit 121 stores a reference value when the projected image is an ideal white display. For example, when the input signal is a 100% white image of the calibration image, the corresponding reference value at the time of 100% white display is stored. By correcting the value of the 1D-LUT 104 or 3D-LUT 103 so that the reference value stored in the sensor reference storage unit 121 is obtained when white 100% is input, the brightness and color of the projection screen are adjusted appropriately. The

  When the input signal includes an image suitable for calibration detected by the image detection unit 122, the comparison calculation unit 116 and the reference value stored in the sensor reference value storage unit 121 and the actual value detected by the color sensor 111. Compare color information on the screen. Then, the comparison calculation means 116 calculates the correction values for the colors and brightness of the various tables stored in the storage unit 102. Then, the comparison calculation unit 116 writes the values of the 1D-LUT 104 and the 3D-LUT 103 in the correction value storage unit 115. The written correction value is sent to the correction update determination means 114, and the value of the 1D-LUT 104 or 3D-LUT 103 is the optimum value (the correction value stored in the correction value storage means 115) at the timing indicated by the control means 118. To correct.

  As a result, even when the calibration image included in the input signal is projected on the screen and the influence of the external light illumination and the color of the screen is added, the brightness and color of the projection screen become the optimum values. Automatic adjustment is performed.

  The above describes the case where correction is performed by automatically detecting a calibration image from the input signal. However, if there is no calibration image, the correction is not executed.

  Therefore, the control means 118 outputs, from the reference image output means 112, for example, a reference image suitable for calibration in which the signal level such as 100% white and 0% black and the region where the signal level exists are known. The reference image is then output to the switch 125, and based on this, calibration correction can be performed in the storage unit 102.

  For example, the value of the 1D-LUT 104 or the 3D-LUT 103 is corrected to the optimum value by forcibly outputting an internal image calibration image and comparing it with the detection value of the color sensor 111 depending on the state of the image projection apparatus. Can do.

  The calibration is performed in a state in which a state that is not inconvenient to the user even if the calibration image is forcibly output, for example, when the input signal is no signal. In addition, for example, when the input signal is switched, when the menu display is switched, when the lamp of the illumination optical system 106 is turned off, when the brightness of the lamp is switched, the reference image is output on the initial screen immediately after the lamp is turned on. Also good. Alternatively, the reference image may be output when the display of the menu for setting the operation of the projector is switched. Alternatively, the reference image may be output when an image mode having an image quality set according to the type of input image such as a movie or sports such as a presentation mode, a standard mode, or a cinema mode is switched. These conditions correspond to the conditions in Table 1 described later.

  FIG. 2 is a flowchart of the automatic color correction method executed by the control means 118. In the automatic color correction method shown in FIG. 2 (including the flows shown in FIGS. 4 and 5 described later), “S” is an abbreviation for step. This correction method can be embodied as a computer-executable program. In this case, the program causes the computer to function as means for performing the following steps.

  First, the lamp of the image projection apparatus is turned on to indicate a normal use state (S1). Next, the setting of the automatic color correction function is executed by a menu operation or the like by an operation with an operation unit such as a remote controller (S2).

  When the automatic color correction setting is selected (Y in S2), as shown in FIG. 3, conditions for executing automatic color adjustment of the input image are set, and an image suitable for color adjustment from the input image signal is set. The signal level and area are set in advance (S3).

  Next, when the input image signal is not suitable for color adjustment, conditions are set for forcibly outputting the reference image (S4). In S4, as shown in Table 1, any or all of the conditions 1 to 5 are selected and set. Note that the calibration image is not limited to white 100%, 50%, and black 0% signals. When there are few time restrictions, R (red), G (green), B (blue), and C ( Cyan), M (magenta), Y (yellow) and each gradation can be increased as necessary.

  When the automatic color correction setting is not selected (N in S2) or after S4, the control unit 118 determines whether or not the condition of S3 is met (S5). When the condition of S3 is met (Y of S5), the control unit 118 compares the sensor reference value with the color sensor value, calculates and stores the correction value, and calibrates the correction value in the table of the storage unit 102. (S6).

  FIG. 4 is a flowchart for explaining details of S6.

  First, the control means 118 determines whether or not the input image is a still image (S61). If it is not a still image (N in S61), the process is terminated. If the image is a still image (Y in S61), the control unit 118 notifies the comparison calculation unit 116 of the input image area and the level via the image detection unit 122 (S62). Next, the control unit 118 causes the color sensor 111 to notify the comparison calculation unit 116 of the area and the detection signal (S63).

  Next, the control unit 118 calculates a correction value for matching the sensor reference value and the color sensor value in the color space of the projector via the comparison calculation unit 116 (S64). The color correction value is used for the 3D-LUT 103, and the luminance correction value is used for the 1D-LUT 104.

  Next, the control means 118 determines whether or not the correction value is within a predetermined range (S65). If it is not within the predetermined range (N in S65), the process is terminated. On the other hand, if the correction value is within the predetermined range (Y in S65), the control unit 118 stores the correction value in the correction value storage unit 115 (S66) and should update the correction value via the correction update determination unit 114. (S67).

  When the correction update determination unit 114 determines that the correction value should not be updated (N in S67), the process ends. On the other hand, when the correction update determination unit 114 determines that the correction value should be updated (Y in S67), the control unit 118 updates the values of the 3D-LUT 103 and the 1D-LUT 104 in the storage unit 102 (S68). The process ends. Thereby, automatic color correction of the input image is performed.

  When the condition of S3 is not met (N of S5) or after S6, the control means 118 determines whether or not the condition of S4 is matched (S7). If the conditions in S4 do not match (N in S7), the process returns to S1.

  On the other hand, when the condition of S4 matches (Y of S7), the control means 118 forcibly outputs the reference image for automatic color correction from the reference image output means 112 via the switch 125 and projects it. (S8).

  Further, the control unit 118 compares the reference projection image with the sensor value, calculates and stores the correction value, and updates the table in the storage unit 102 (S9). FIG. 5 is a flowchart for explaining details of S9.

  First, the control means 118 notifies the comparison calculation means 116 of the detection result of the color sensor 111, the image area designated by the image area designation means 120, and the detection signal (S91). Next, the control means 118 calculates a correction value for matching the sensor reference value and the color sensor value in the projector color space (S92).

  Next, the control means 118 determines whether or not to change the reference image (S93). When changing the reference image (Y in S93), the reference image is changed and projected (S94). Return. On the other hand, if the reference image is not changed (N in S93), it is determined whether or not the correction value is within a predetermined range (S95). If the correction value is not within the predetermined range (N in S95), The process ends.

  On the other hand, if the correction value is within the predetermined range (Y in S95), the control unit 118 stores the correction value in the correction value storage unit 115 (S96), and the values of the 3D-LUT 103 and 1D-LUT 104 in the storage unit 102 are stored. Is updated (S98), and the process is terminated. Thereby, automatic color correction of the reference image is performed.

  The color reproduction operation executed using the image comparison calculation unit 123 and the storage unit 102 is as follows. That is, the control unit 118 is configured to input the color space of the image projection apparatus based on the color information RGB or XYZ values on the screen 110 captured from the color sensor 111 and the color space on the input signal side based on the color information of the input image (for example, , SRGB color space). And the control means 118 produces | generates the table correction value of the memory | storage part 102 so that it may become the same color as an input signal under the influence of a wall color, the color of the screen 110, and illumination light.

  According to the present embodiment, when the signal level and region of an image suitable for color correction are registered from the input image, automatic color correction is sequentially performed by detecting the conditions of the input image, and an image suitable for color correction cannot be detected. However, automatic color correction can be performed by outputting a reference image according to conditions. For this reason, automatic color correction is performed by calculating and updating the correction values of the 3D-LUT 103 and the 1D-LUT 104 even when the screen is colored without any special operation of the user only by the initial setting or when the illumination light changes. can do. Further, an automatic color correction function can be realized by using an input signal condition suitable for calibration, a reference screen, and a color sensor reference value adjusted by factory adjustment or the like according to a predetermined external light condition.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  The image projection apparatus of this embodiment can be applied to uses such as a liquid crystal projector.

118: Control means (color correction means, calibration means), 126 ... Storage means

Claims (9)

An image projection apparatus for projecting an image onto a projection surface,
Color correction means for correcting the color of the input image using the color correction table, and correcting the luminance of the input image using the luminance correction table;
Calibration for calibrating the respective correction values held in the color correction table and the luminance correction table so that the color information of the input image and the color information of the reflected light of the image projected on the projection surface match. Means,
Storage means for storing a signal level of a calibration image for performing the calibration and an area where the calibration image exists on the projection plane;
Control means for executing calibration by the calibration means and color correction by the color correction means on condition that the calibration image is included in the input image;
An image projection apparatus comprising: Output means for outputting the calibration image;
The image projecting apparatus according to claim 1, wherein when the output unit outputs the calibration image, the control unit causes the calibration unit to perform calibration and the color correction unit to perform color correction.   The image projecting apparatus according to claim 2, wherein the output unit outputs the calibration image when the input image is switched. An illumination optical system that illuminates a display element that displays an image corresponding to the input image;
The output means is used for the calibration either when the lamp of the illumination optical system is turned off, when the brightness of the lamp is switched, or when an initial screen immediately after the lamp is turned on is projected. The image projection apparatus according to claim 3, wherein an image is output. An image mode having an image quality set according to the type of the input image;
The image projecting apparatus according to claim 3, wherein the output unit outputs the calibration image when the image mode is switched. A menu for setting the operation of the image projection apparatus;
The image projecting apparatus according to claim 3, wherein the output unit outputs the calibration image when the display of the menu is switched.   7. The control unit according to claim 1, wherein the control unit executes calibration by the calibration unit and color correction by the color correction unit on the condition that the input image is a still image. The image projection apparatus according to item. A color correction method that is used in an image projection apparatus that projects an image on a projection surface, corrects the color of an input image using a color correction table, and corrects the brightness of the input image using a brightness correction table. There,
The step of calibrating the correction values held in the color correction table and the luminance correction table so that the color information of the input image and the color information of the reflected light of the image projected on the projection surface coincide with each other. When,
Storing a signal level of a calibration image for performing the calibration and a region where the calibration image exists on the projection plane;
Automatically executing calibration and color correction on condition that the input image includes the calibration image;
A color correction method comprising: It is used in an image projection apparatus that projects an image onto a projection surface, and the computer of the image projection apparatus corrects the color of the input image using a color correction table, and uses the brightness correction table to correct the input image. A program for executing a color correction method for correcting luminance,
The computer,
Means for calibrating respective correction values held in the color correction table and the luminance correction table so that the color information of the input image and the color information of the reflected light of the image projected on the projection surface coincide with each other. ,
Means for storing a signal level of a calibration image for performing the calibration and a region where the calibration image exists on the projection plane;
Means for automatically executing calibration and color correction on condition that the input image includes the calibration image;
Program to function as.